The present invention relates to a vehicle brake control system capable of producing different degrees of braking force in response to the input of a brake foot pedal.
A known vehicle brake control system is operable to produce a braking force even when a brake pedal is not depressed and develop a braking force greater than a force normally obtained when the brake pedal is depressed. Such a conventional brake control system is adapted to provide traction control (TCS) and vehicle dynamic control (VDC). In the traction control mode, a controller receives information typically on wheel speed and wheel cylinder brake pressure, provided that the input of the brake pedal is absent, and brings brake pressure in wheel cylinders to the desired level so as to avoid wheel spin. In the vehicle dynamic control mode, the controller receives information typically on the actual yaw rate, lateral acceleration and steering wheel angle (or position), regardless of whether or not the input of the brake pedal is available, and brings the yaw rate to the desired rate. Conventionally, a mechanical pump is employed to increase brake pressure in the wheel cylinders. The system as a whole is thus costly.
Accordingly, it is an object of the present invention to provide a vehicle brake control system which does not require a mechanical pump to increase wheel cylinder brake pressure and is thus economical to manufacture.